The assignee for this patent application is
Reporters obtained the following quote from the background information supplied by the inventors: "The present invention relates to methods and apparatus for removing and remodeling lateral recess and neural foramina enlargement of the spine. More specifically, it relates to removal of tissue or bone from the lateral recess, neural foramina and central spinal canal areas using ultrasound or other tools.
"Pathological compression of spinal neural and neurovascular structures most commonly results from a degenerative, age-related process, increasing in prevalence and severity in elderly populations, with potential congenital anatomic components, that result in back, radicular extremity pain and both neurological (e.g., sensory) and mechanical (e.g., motor) dysfunction. Prevalence is also influenced by congenital spinal anatomy. This disease progression leads to increased neural irritation, neural and neurovascular impingement, and ischemia, and is frequently accompanied by progressively increased pain, often in conjunction with reflex, sensory and motor neurological deficits.
"Current surgical treatments for spinal stenosis include laminectomy (usually partial, but sometimes complete), laminotomy and/or facetectomy (usually partial, but sometimes complete), with or without fusion. While standard surgical procedures (e.g., spinal decompressions) lead to improvements in symptoms for 6 months or more in approximately 60% of cases, there is an unacceptable incidence of long-term complications and morbidity: approximately 40% of patients do not obtain sustained improvement with current surgical decompressions.
"There are several tools that facilitate surgical access to the areas of the spine where neural impingement is likely to occur, in order to allow the surgeon to decompress the impinged neural structures through the removal of vertebral lamina, ligamentum flavum, facet complex, bone spurs, and/or intervertebral disc material. These surgical resections are frequently (i.e., occurs in 15% to 20% of cases) accompanied by fusion (arthrodesis). Spinal arthrodesis is performed to fuse adjacent vertebrae and prevent movement of these structures in relation to each other. The fusion is commonly a treatment for pain of presumed disc or facet joint origin; for severe spondylolisthesis; for presumed spinal instability; and for spines that have been rendered 'unstable' by the surgical decompression procedures, as described above. The definition of 'spinal instability' remains controversial in current literature.
"Spinal arthrodesis may be achieved through various surgical techniques.
"Critics have frequently stated that while discectomy and fusion procedures frequently improve symptoms of neural impingement in the short term, both are highly destructive procedures that diminish spinal function, drastically disrupt normal anatomy, and increase long-term morbidity above levels seen in untreated patients.
"The high morbidity associated with discectomy may be due to several factors. First, discectomy reduces disc height, causing increased pressure on facet joints. This stress leads to facet arthritis and facet joint hypertrophy, which then causes further neural compression. The surgically-imposed reduction in disc height also may lead to neuroforaminal stenosis, as the vertebral pedicles, which form the superior and inferior borders of the neural foramina, become closer to one another. The loss of disc height also creates ligament laxity, which may lead to spondylolisthesis, spinal instability or osteophyte or 'bone spur' formation, as it has been hypothesized that ligaments may calcify in their attempt to become more 'bone-like'. In addition, discectomy frequently leads to an incised and further compromised disc annulus. This frequently leads to recurrent herniation of nuclear material through the surgically created or expanded annular opening. It may also cause further buckling of the ligamentum flavum. The high morbidity associated with fusion is related to several factors. First, extensive hardware implantation may lead to complications due to breakage, loosening, nerve injury, infection, rejection, or scar tissue formation. In addition, autograft bone donor sites (typically the patient's iliac crest) are a frequent source of complaints, such as infection, deformity, and protracted pain. Perhaps the most important reason for the long-term morbidity caused by spinal fusion is the loss of mobility in the fused segment of the spine. Not only do immobile vertebral segments lead to functional limitations, but they also cause increased stress on adjacent vertebral structures, thereby frequently accelerating the degeneration of other discs, joints, bone and other soft tissue structures within the spine.
"Recently, less invasive, percutaneous approaches to spinal discectomy and fusion have been tried with some success. While these less invasive techniques offer advantages, such as a quicker recovery and less tissue destruction during the procedure, the new procedures do not diminish the fact that even less invasive spinal discectomy or fusion techniques are inherently destructive procedures that accelerate the onset of acquired spinal stenosis and result in severe long-term consequences.
"Additional less invasive treatments of neural impingement within the spine include percutaneous removal of nuclear disc material and procedures that decrease the size and volume of the disc through the creation of thermal disc injury. While these percutaneous procedures may produce less tissue injury, their efficacy remains unproven.
"Even more recently, attempts have been made to replace pathological discs with prosthetic materials. While prosthetic disc replacement is a restorative procedure, it is a highly invasive and complex surgery. Any synthetic lumbar disc will be required to withstand tremendous mechanical stresses and may require several years of development. Current synthetic disc designs cannot achieve the longevity desired. Further, synthetic discs may not be an appropriate therapeutic approach to a severely degenerative spine, where profound facet arthropathy and other changes are likely to increase the complexity of disc replacement. Like most prosthetic joints, it is likely that synthetic discs will have a limited lifespan and that there will be continued need for minimally invasive techniques that delay the need for disc replacement.
"Even if prosthetic discs become a viable solution, the prosthetic discs will be very difficult to revise for patients. The prosthesis will, therefore, be best avoided in many cases. A simpler, less invasive approach to restoration of functional spinal anatomy would play an important role in the treatment of neural impingent in the spine. The artificial discs in U.S. clinical trials, as with any first generation prosthesis, are bound to fail in many cases, and will be very difficult to revise for patients. The prostheses will, therefore, be best avoided, in many cases. Lumbar prosthetic discs are available in several countries worldwide.
"In view of the aforementioned limitations of prior art techniques for treating neural and neurovascular impingement in the spine, it would be desirable to provide methods and apparatus for selective surgical removal of tissue that reduce or overcome these limitations.
"The present invention provides a method that allows for the removal of the offending tissue, primarily bony and soft tissue, in any joint in the body without causing iatrogenic instability to the patient. One method described herein addresses the treatment of a specific joint/neural impingement in the spine known as spinal stenosis. The methods and apparatus described herein can be applied to a variety of nerve stenosis areas in the body, including the hand, wrist, foot, knee, shoulder, neck etc.
"Traditional surgical techniques for the treatment of spinal stenosis involve the removal of all the offending tissue pressing on the cauda equina (C.E) or the nerve root (bone & ligament). This common surgical technique uses tools such as the rongeur or rotary drill (i.e., Midas Rex by
"At least two commercially used MIS procedures have been developed to address the limitations of traditional spinal decompression surgery techniques, but the challenges of direct visualization or a visualization surrogate are still required to avoid inadvertent damage to the neural structure. One MIS procedure involves the use of endoscopy for visualization (
"The present invention addresses the iatrogenic instability limitations of the common 'invasive' surgical procedures and many of the practical adoption challenges associated with the known MIS procedures. In particular, the invention avoids the need for complicated visualization methods (endoscopy) or visualization surrogates (stimulation/EMG) by ensuring that the trajectory of the cutting devices are always dorsai to the exiting nerve root, and/or that the cutting devices used in this procedure only cut hard tissue (i.e. bone or calcified ligament or disc) and do not cut soft tissue such as nerve, dura, blood vessels or muscle.
BRIEF DESCRIPTION OF THE DRAWINGS
"FIG. 1 illustrates a lateral view of a model that demonstrates lateral stenosis. The model shows the stenosis between the ventral aspect of the SAP and the dorsal aspect of the disc and vertebral body (VB). The stenosis is demonstrated by the nerve root being compressed by the ventral aspect of the SAP.
"FIG. 2 illustrates a model showing lateral recess and foraminal stenosis.
"FIGS. 3 and 4 are two views illustrating a first step of a tissue removal method according to a first embodiment of the present invention through the use of a model, where the trajectory of the medial to lateral bore hole is created.
"FIGS. 5 and 6 are two other views illustrating the first step of a tissue removal method according to the first embodiment of the present invention through the use of a model, where a medial to lateral bore hole is created.
"FIGS. 7 and 8 are two views illustrating a second step of a tissue removal method according to the first embodiment of the present invention through the use of a model, the ventral aspect of SAP.
"FIG. 9 is a lateral view of the model in FIGS. 7 and 8.
"FIGS. 10 and 11 are two views illustrating a third step of a tissue removal method according to the first embodiment through the use of a model, the removal of a slice of tissue.
"FIG. 12 illustrates a tissue removal method according to a second embodiment of the present invention through the use of a model.
"FIGS. 13 and 14 illustrate a tissue removal method according to a third embodiment of the present invention through the use of a model.
"FIG. 15 illustrates a tissue removal method according to a fourth embodiment of the present invention through the use of a model.
"FIG. 16 is a schematic of a lumbar spine showing the two possible trajectories of the burr hole through the SAP: either the straight trajectory (Rt. Path A) or the curved trajectory (Rt. Path B).
"FIG. 17 is a cross-sectional view of a clutched deployable rotary device for head-on cutting.
"FIG. 18 is a cross-sectional view of the device of FIG. 17 shown in operation.
"FIG. 19 is a cross-sectional view of a clutched and telescoping cutting device according to another embodiment of the present invention.
"FIG. 20 illustrates the operation of the spring element of the device in FIG. 19.
"FIG. 21 is a cross-sectional view of a clutched side-cutting rotary device according to the present invention.
"FIG. 22 is a cross-sectional view of a clutched side-cutting device with multiple cutting elements according to the present invention.
"FIGS. 22AA and 22BB are cross-sectional views taken along the lines AA and BB, respectively, in FIG. 22.
"FIG. 23 is a cross-sectional view of an ultrasonic cutter according to the present invention.
"FIG. 24 is a cross-sectional view of the device of FIG. 23 shown in operation.
"FIGS. 25 and 26 illustrate two different types of side-cutting ultrasonic cutters."
In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "The present invention provides a method of cutting and removing a portion of a tissue structure which is directly or indirectly impinging on a neural structure. According to the method, a first channel is created through the majority of the tissue structure's cross section, and then through the first channel, a second channel is created orthogonal to the first channel where the second channel extends from the first channel to an edge of the tissue structure to define a tissue portion for removal. The tissue portion is then detached from the tissue structure"
For more information, see this patent application:
Keywords for this news article include: Patents, Treatment.
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